Arclight Phoenix with Drowned Secrets has always been one of our favorite strategies since the cards were printed, but Theros Beyond Death gives the deck access to the extremely broken Underworld Breach, giving it an incredible power boost.
Arclight Phoenix with Underworld Breach
1 Thassa's Oracle 1 Glimpse of Freedom 4 Drowned Secrets 4 Arclight Phoenix 4 Radical Idea 4 Opt 4 Narcomoeba 4 Creeping Chill 4 Merfolk Secretkeeper/Venture Deeper 4 Unsummon 1 Sweet Oblivion 1 Maximize Altitude 4 Underworld Breach 12 Island (335) 4 Temple of Epiphany 4 Steam Vents
Arena-Formatted Phoenix Breach Decklist Deck
1 Thassa's Oracle (THB) 73
1 Glimpse of Freedom (THB) 50
4 Drowned Secrets (GRN) 39
4 Opt (XLN) 65
4 Arclight Phoenix (GRN) 91
4 Radical Idea (GRN) 52
4 Narcomoeba (GRN) 47
4 Creeping Chill (GRN) 66
12 Island (ANA) 62
4 Merfolk Secretkeeper (ELD) 53
4 Unsummon (M20) 78
1 Sweet Oblivion (THB) 70
1 Maximize Altitude (GRN) 43
4 Underworld Breach (THB) 161
4 Temple of Epiphany (M20) 253
4 Steam Vents (GRN) 257
The core of the deck is the same as we've discussed in previous articles. Drowned Secrets is by far the most important card and is worth mulliganing passable hands to dig for it. Merfolk Secretkeeper plus Unsummon gives us a ton of blue spells to cast, as well as some early gameplay when we are lacking our key enchantment. This package also gives us a critical mass of 1-mana spells in order to easily return Arclight Phoenix early.
Underworld Breach is one of those cards that everyone instantly knows that it's broken when they read it. It's sure to find a home in combo decks in nonrating formats, but it's also great in Standard. It's obviously at its best when you can fill your graveyard, which this deck does every single game. It's also great when your key cards are a bunch of one mana spells or you rely on a specific card, as you can get more value out of it. It can be played on five mana to simply get back Arclight Phoenix with three one-mana spells, or it can be played to return one or more copies of Drowned Secrets to the battlefield, setting you up for future turns. Considering the fact that we used to run Mission Briefing in this type of deck, we're happy to have such a massive upgrade.
Sweet Oblivion and Glimpse of Freedom are a couple of sweet new tools from Theros as well. Escape cards are obviously busted when the graveyard cost is trivial. However, we haven't opted to run too many copies of them in this build, as we mill so many cards from our deck that we only need a copy or two in order to find access to them regularly. Glimpse of Freedom makes it very difficult to flood out in a longer game, and Sweet Oblivion gives us just enough extra juice that we can always get our engines running even in games where we are missing Drowned Secrets.
Creeping Chill has always been worth the slot in this deck due to its combined ability to keep us alive against aggro and speed up our clock, but Narcomoeba is a card that we've been back and forth on. Underworld Breach and the escape cards seem to give us so much consistency and flexibility that it seems fine to run the extra "dead" cards, but if more testing proves that they are a liability then they can be trimmed or cut for more card draw or interaction. One minor but important interaction worth noting is that they provide a free creature on the battlefield that could be the difference between being able to reanimate Phoenix or not if you have copies of Unsummon or Maximize Altitude that you would be otherwise unable to cast.
Lastly, how could we fail to mention Thassa's Oracle? We may have won more games through this creature's trigger than through normal damage since Theros with our addiction to brews using this card, but it works great in this deck as a backup plan. While we usually just kill through Phoenix and Creeping Chill damage, a single copy of this card (effectively five copies due to Underworld Breach) means that we can simply win the game in those weird situations where the damage plan doesn't work.